Selcan ÖZTÜRK, Serdar KULA
Trends in Pediatrics - 2026;7(1):26-33
Objective: The pulmonary arterial capacitance index (PACi) has recently emerged as a dynamic marker of pulmonary vascular compliance. However, its clinical relevance in pediatric pulmonary arterial hypertension (PAH), and particularly its relationship with functional capacity and exercise tolerance in congenital heart disease (CHD), remains unclear. This study explored these associations and assessed changes following PAH-specific therapy. Materials and Methods: Thirty-five patients with CHD-associated PAH with a mean pulmonary artery pressure (mPAP)>=20 mmHg receiving PAH-specific therapy and 35 age-, sex-, and anthropometry-matched CHD controls without PAH were evaluated. Demographic characteristics, hemodynamic parameters, PACi, functional class, brain natriuretic peptide (BNP) levels, and six-minute walk test (6MWT) distances were compared. Pre- and post-treatment hemodynamic and clinical parameters were also analyzed in the PAH group. Results: Ventricular septal defect was the most common CHD in both groups. Children with PAH had significantly higher mPAP and pulmonary vascular resistance index (PVRi) and lower PACi than controls. PACi was inversely correlated with mPAP (r=-0.383, p=0.023) and PVRi (r=-0.812, p<0.01) but exhibited no significant association with BNP or 6MWT distance. No significant improvement in PACi or PVRi was observed after treatment. Conclusion: PACi may serve as an early indicator of pulmonary vascular stiffness in pediatric PAH. Its limited association with functional and exercise-based assessments likely reflects early disease stages, age-related variability, and measurement constraints. Persistently low PACi and PVRi despite therapy underscore the progressive nature of pediatric PAH and highlight the need for larger, long-term prospective studies.
